Systems and methods for controlling a fluid based engineering system are disclosed. The systems and methods may include a model processor for generating a model output, the model processor including a set state module for setting dynamic states of the model processor, the dynamic states input to an open loop model based on the model operating mode. The system may include a control law for directing the actuator as a function of a model output and for determining if the control device is operating with deteriorated conditions. The model processor may further include an estimate state module for determining an estimated state of the model based on a prior state model output and the current state model of an open loop model.